CO2 emissions

CO2 emissions to the atmosphere occur naturally.

Carbon dioxide is released

• through respiration by animals and plants
• through microbial metabolism during decomposition of dead organic matter
• by exchange at the water surface between the oceans and atmosphere
• in volcanic eruptions

Each year roughly 550,000 million tCO2e pass from these sources to the atmosphere.

However, a similar amount is absorbed back to the land and oceans

• through photosynthesis by land plants and oceanic phytoplankton and
• by direct exchange at the ocean surface

This is the essence of the global carbon cycle and it is roughly in balance.

Each year human activities generate around 26,000 million tCO2e of greenhouse gas emissions or just less than 5% of the natural flux.

However, only about half of this reaches the atmosphere.

The rest is absorbed in the ocean and vegetation on land.

There are just a few human activities that do the opposite and pull carbon out of the atmosphere and sequester CO2.

We do grow some plantation trees that can capture CO2 and prudent soil management can sequester up to one tCO2e per hectare per year, especially in degraded soils.

Generally, however, our vegetation and soil management is a net source of emissions. This is because land management priorities are the production of food and fibre for humans and livestock.

For farmers it is usually more about balancing a financial budget than a carbon budget.

To achieve reliable production we also use fertilizers that release nitrous oxide (N2O) a greenhouse gas 114 times more potent than CO2.

Our livestock also belch methane (CH4) that is 12 times more potent.

Why we are focused on emissions?

Atmospheric concentrations of CO2 have increased from 280 ppmv (parts per million by volume) to 391 ppmv (February 2011 estimate) since the start of the industrial revolution.

The correlation between CO2 emissions and carbon dioxide concentration in the atmosphere exists.

The physics of warming potentials in these gases makes the logic obvious. Higher CO2 concentrations will warm the planet.

The IPCC reports conclude that this is "highly likely".

More energy in the atmosphere and ocean systems leads to funky climates, some severe weather events and rising sea levels . In time, a series of specific effects that have a bearing on our economic potential.

So the plan becomes, reduce emissions.

Easier said than done because the bulk of CO2 emissions come from a combination of burning of fossil fuels for energy generation and transport, plus land clearing for food production. Emission reduction is hard simply because these things are fundamental to us.

Just to keep emissions stable is task enough when the human population is growing in number at 8,000 per hour and greater affluence is both desired and, mostly, being achieved.

Business as usual will mean greater not lower emissions.

Notionally then, we need to change the way we do business. This is the essence of the carbon trading concept where by putting a price on emissions (an additional cost of doing business) it makes business as usual so expensive that there is no choice but a shift to cheaper, cleaner alternatives, especially for energy and transport.

Food production, when done well, can be a net carbon sink through biosequestration and in carbon trading, sequestration generates carbon credits.

Sounds like a good plan.

So why do we not have carbon trading schemes going gangbusters all around the world?

It is because business as usual is always cheaper and more competitive than systems with an imposed carbon price.

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